Spinal fixation devices are used in orthopedic surgery to align and/or fix a desired relationship between adjacent vertebral bodies. Such devices typically include a spinal fixation element, such as a relatively rigid fixation rod, that is coupled to adjacent vertebrae by attaching the element to various anchoring devices, such as hooks, bolts, wires, or screws. Alternatively, two rods can be disposed on the lateral or anterior surface of the vertebral body in a substantially parallel relationship. The fixation rods can have a predetermined contour that has been designed according to the properties of the target implantation site, and once installed, the rods hold the vertebrae in a desired spatial relationship, either until desired healing or spinal fusion has taken place, or for some longer period of time.
Several plate and screw systems have been designed for instrumentation of the spinal column. A typical construct utilizes vertebral staples, spinal screws and locking nuts, and two spinal fixation rods. A staple is implanted in each adjacent vertebra and two screws are inserted through holes formed in the staple such that the screw heads rest against the staple. The spinal fixation rods are then positioned within the screw heads such that the rods are substantially parallel to one another and they span across multiple adjacent vertebrae. The rods are then locked in place using the locking nuts, thereby maintaining the vertebrae in a fixed position.
Most vertebral staples are used to impair toggling action by the screws implanted therethrough, and they are intended to prevent motion which can cause the screw to bone interface from breaking down. Each vertebral staple typically includes two or more spikes, often placed on each corner of the staple, to secure the staple to a vertebra. The staple is implanted in the vertebra by positioning it against the vertebra and applying a force thereto to impact the staple into the bone.
While current vertebral staples are effective, one drawback is that they do not allow the position of the staple to be adjusted once the staple is implanted in the vertebra. If the staple is not properly aligned, the surgeon is required to remove the staple and re-position it. One other draw back of current vertebral staple designs is that they can be difficult to manipulate using existing insertion tools. In particular, most vertebral staples are not planar, but rather they have uneven surfaces. As a result, it can be difficult to grasp the staple using an insertion tool, and to evenly impact the staple into the vertebra.
Accordingly, there remains a need for an improved vertebral staple that includes features which allow the position of the staple with respect to the vertebra to be adjusted prior to fully implanting the staple. There also remains a need for improved methods and devices for grasping and implanting a vertebral staple.